This invention relates to method and apparatus for optically detecting information from a recording medium in which pits are locally formed by thermal energy of a light spot to record the information, and more particularly to an optical detection method and apparatus for stably detecting information from a recording medium which has the information at positions where pits have been recorded.
An example of an optical information recording/reporting apparatus having information at center positions of hole-like pits is disclosed in an article entitled "Ten Billion Bits on a Disc", IEEE, SPECTRUM, Aug., 1979. Conventionally, in this type of apparatus, conditions required of pit size and reproduction light spot size for stable detection of information have not been known and a detection method capable of stably detecting the information has also been unknown.